1. Field of the Invention
The invention relates to an automatic, virtually leak-free filling system for filling a liquid tank, comprising a bulk supply tank, a liquid line at one end connected to the bulk supply tank and at the opposite end fitted with coupling means for a manually detachable, virtually leak-free coupling to a filling neck of a liquid inlet to a liquid tank, pump means for transport of liquid from the bulk supply tank to the liquid tank, and comprising overfill protection means for automatically cutting of the liquid supply to the liquid tank when a predetermined filling level has been reached in the liquid tank. The invention furthermore relates to an adaptor and a pressure pulse valve for use in such a system.
In this respect it is noted that both the liquid tank and the bulk supply tank may be either stationary or mobile. The liquid tank may for instance be a vehicle fuel tank which is to be filled from a bulk supply tank of a refuelling station. However likewise it is for instance possible that the liquid tank is stationary and is filled from a mobile bulk supply tank of for instance a tank lorry, wagon or ship. Moreover the invention is not limited to a system for filling fuels but may likewise be applied for filling of other liquids.
The leakage of liquids often poses a considerable threat to the environment. By using a system of the type described in the opening paragraph, such threat can be avoided as said system provides for virtually leak-free filling so any spilling of liquid is counteracted. This is of course of particular interest for liquids which may pollute the environment such as fuels and harmful chemicals. However, also for liquids which are less harmful to the environment may a system of the type referred to in the opening paragraph be used advantageously, as in any case waste of the liquid concerned is avoided.
2. Description of the Related Art
An existing automatic, virtually leak-free filling system, used for filling vehicle fuel tanks from a bulk supply tank, comprises pump means in the form of a pump installation whereby fuel is pumped from the bulk supply tank to the vehicle fuel tank via a flexible fuel hose. The fuel hose is coupled virtually leak-free to a filling neck of the vehicle tank by means of a virtually leak-free quick-connection coupling which is mounted to the open end of the fuel hose. To prevent the fuel tank from being overfilled, the existing system contains overfill protection means in the form of an electronic liquid sensor which is contained in the vehicle fuel tank. When the fuel in tank reaches said sensor, it produces an electrical output signal that causes the supply of further fuel to be stopped automatically.
The existing automatic, virtually leak-free filling system has however the drawback that the liquid sensor has to be built into the vehicle fuel tank, which therefore has to be opened up. Especially for existing vehicles, this causes considerable costs due to the rather long time needed for fitting and the associated withdrawal from operation of the vehicle. Moreover, the liquid sensor used reacts rather slowly, which renders the existing system less suitable for filling at relatively high rates up to, for example, 150 litres per minute. At such high filling rates the further supply of fluid needs to be cut off extremely fast, particularly to avoid that the pressure within the liquid tank does not rise to an inadmissible level. A further drawback of the known system is the necessity of a separate electrical connection to the (sensor within) the liquid tank. When this connection is forgotten, at the best merely liquid will run out of the liquid tank once its maximum filling level is exceeded but it is even possible that the liquid tank will explode due to an inadmissible rise of its internal pressure.